An in vivo confocal microscopy analysis of effects of topical antiglaucoma therapy with preservative on corneal innervation and morphology

Abstract

Purpose: To evaluate the long-term effects of preservative-free and preservative-containing antiglaucoma eye drops on the tear secretion and ocular surface.

Design: Comparative retrospective study.

Methods: A total of 84 patients with bilateral primary open-angle glaucoma or ocular hypertension divided into 5 groups according to type of topical hypotensive therapy and 20 healthy age-matched volunteers were studied. Clinical tests (corneal sensitivity, Schirmer I test, and lachrymal film break-up time), and in vivo confocal microscopy were performed in all patients.

Results: A significant reduction of the scores was found between groups on topical hypotensive therapy and the control group in all clinical parameters studied (P < .05). In particular, the clinical scores were significantly lower in the preservative medication groups than in the preservative-free group (P < .05). The density of superficial epithelial cells was reduced in all glaucomatous patients, except for the preservative-free group (P > .05), with respect to control subjects (P < .001). On the contrary, the density of basal epithelial cells of glaucomatous preservative therapy groups was higher than control and preservative-free groups (P < .05). Stromal keratocyte activation and the number of beads were higher in all glaucoma preservative groups (P < .05). The number of sub-basal nerves was lower in all glaucoma groups than in the control group (P < .05) and tortuosity was significantly higher in glaucoma than control groups (P < .05). Reflectivity of fibers did not show any significant difference between the 6 groups (P < .05).

Conclusions: Glaucomatous patients with chronic treatment show ocular surface alterations. The development of nontoxic antiglaucoma treatment may reduce damage to the ocular surface and improve the compliance and the adherence in the medical therapy.